Manual scanning mechanism for video disc player

ABSTRACT

A video disc player includes a turntable for centering and rotatably supporting a record for playback. A pickup stylus for recovering information stored on a turntable-supported record is mounted in a compartment provided in a carriage. A common drive belt is provided for selectively translating the carriage. The player is equipped with a first drive mechanism for utilizing the common drive belt for translating the carriage during playback toward the turntable center at a speed correlated to the speed of rotation of the turntable while stylus/record engagement is permitted. A second drive mechanism is employed for utilizing the common drive belt for translating the carriage during active searching toward and away from the turntable center at a speed independent of the speed of rotation of the turntable while the stylus is riding on the record. The first drive mechanism includes a slip clutch interposed between the common drive belt and the turntable drive motor, whereby wresting of control of the common drive belt by the second drive mechanism from the first drive mechanism is allowed by the slip clutch upon activation of the second drive mechanism.

This invention generally relates to video disc players, and moreparticularly, to player mechanisms for providing active scanning, aswell as special effects (such as: repeat play, fast forward and reversemotion).

In certain video disc systems, information is stored on a disc record inthe form of geometric variations in the bottom of a continuous spiralgroove disposed on the record surface. The variations in capacitancebetween an electrode incorporated in a groove-riding stylus and aconductive coating disposed on the record surface are sensed toreproduce the stored information. A capacitance-type video disc systemis illustratively disclosed in U.S. Pat. No. 3,842,194 (Clemens).

In such systems, it is advantageous to mount a groove-riding pickupstylus in a demountable cartridge. The player is provided with rails forguiding a carriage, having a compartment for receiving the pickupcartridge, along a path. The carriage is driven during playback alongthe carriage guiding rails in correlation with the motion of thegroove-riding stylus. U.S. Pat. No. 3,870,320 (Torrington), discloses atype of carriage translating system.

It is beneficial to enclose a record in a thin plastic caddy. For recordloading, an occupied caddy is inserted into an input slot provided inthe player. The player is equipped with another set of rails for guidingcaddy insertion along a further path. A record extracting mechanismdisposed in the player removes the record from the caddy duringsubsequent caddy withdrawal, whereby the record is retained in theplayer. The player is equipped with a platform for supporting theretained record when it is disposed in an elevated position. Theretained record is transferred to the turntable for playback duringmotion of the platform to a depressed position. For subsequent recordretrieval, the platform, with the retained record resting thereon, israised, and an empty caddy is inserted into the player, therebyreturning the record back into the caddy. Withdrawal of the caddy,effects record removal from the player. U.S. Pat. No. 4,098,511(Leedom), and patent applications, Ser. Nos. 747,729 (Coleman), now U.S.Pat. No. 4,124,866, and 801,604, (Torrington), now U.S. Pat. No.4,133,340, illustrate systems suitable for use with a record caddy. Theabove patent and applications are assigned of record to the assignee ofthe instant application.

In such systems, the carriage is typically mounted for side-to-sidemotion and the direction of caddy insertion is from front-to-back, adirection which is orthogonal to the carriage path. Such configurationimposes several constraints on player design and construction: forexample, it is necessary that the starting position of the carriage isbeyond the record periphery, one of the caddy guiding rails is mountedon the carriage to prevent interference thereof with the motion of thecarriage toward the record center; a separate mechanism is needed toreturn the carriage to the starting position subsequent to playback; anda stylus landing adjustment mechanism is necessary to insure that thestylus is lowered precisely over the beginning of the recorded bandduring travel of the carriage from an off-record starting positiontoward a position overlying the record.

In a concurrently filed, copending application, Ser. No. 964,531, of L.A. Torrington, entitled "VIDEO DISC PLAYER," a novel video disc playerconstruction, which overcomes the hereinbefore mentioned constraints, isdisclosed. In the therein disclosed system, the carriage is translatedalong a path disposed substantially parallel to the path of caddyinsertion. Pursuant to a further feature of the Torrington invention,the direction of translation of the carriage during playback is oppositeto the direction of the caddy insertion. The location of the caddy pathrelative to the carriage path is such that the caddy engages thecarriage, when the carriage is at a position other than at a startingposition, during a caddy insertion to reset the carriage at the startingposition. The Torrington application is assigned of record to theassignee of the instant application.

In video disc players of the type mentioned above, it is desirable toprovide active searching, as well as special effect features (such as:repeat play, fast forward and reverse motion). In a concurrently filed,copending U.S. patent application, Ser. No. 964,534, of F. R. Stave andentitled "VIDEO DISC PLAYER HAVING MANUAL SCAN FACILITY," a carriagetranslating apparatus for providing active searching and special effectsis described. The therein disclosed carriage translating apparatusincludes a unidirectional play belt for translating the carriage towardthe turntable center at a speed correlated to the turntable rotationalspeed, a bidirectional search belt for translating the carriage towardand away from the turntable center at a speed independent of theturntable rotational speed, and a selectively actuated apparatus forclamping one of the two belts to the carriage to effect carriagetranslation by a selected one of the belts to the exclusion of the otherof the belts.

A system, in accordance with the instant invention, provides activescanning and special effect features without the need for two separateplay and search belts and without the need for clamping and unclampingthe belts. Pursuant to the present invention, a common drive belt,fixedly secured to the carriage, is provided. The player is equippedwith a first drive mechanism for utilizing the common drive belt fortranslating the carriage during playback toward the turntable center ata speed correlated to the turntable speed. A second drive mechanism isemployed for utilizing the common drive belt for translating thecarriage during active scanning toward and away from the turntablecenter at a speed independent of the turntable rotational speed. Thefirst drive mechanism incorporates a slip clutch interposed between apulley which drives the common drive belt and a pulley driven by theturntable motor, whereby wresting of control of the common drive belt bythe second drive mechanism from the first drive mechanism is permittedby the slip clutch upon actuation of the second drive mechanism.

IN THE DRAWINGS

FIG. 1 is a plan view of a video record player incorporating thecartridge translating apparatus of the aforesaid Stave application;

FIG. 2 is a perspective end view of the player of FIG. 1, with adepressible platform being shown in the raised position;

FIG. 3 is a perspective end view of the player of FIGS. 1 and 2, withthe depressible platform being shown in the lowered position;

FIGS. 4 and 5 depict a record caddy, comprising a jacket and a recordretaining member, suitable for use with the player of FIGS. 1-3;

FIG. 6 illustrates a record extracting mechanism disposed in the playerof FIGS. 1-3;

FIGS. 7 and 8 show the operation of the record extracting mechanism ofFIG. 6;

FIGS. 9 and 10 demonstrate the sequence involved in transferring arecord, resting on the depressible platform of FIGS. 1-3, to the playerturntable;

FIG. 11 illustrates a stylus lifting/lowering apparatus suitable for usewith the player of FIGS. 1-3;

FIG. 12 illustrates a novel carriage translating mechanism pursuant tothe principles of the present invention, and which can be substitutedfor the carriage translating mechanism disclosed in the abovesaid Staveapplication in the player of FIGS. 1-3; and

FIG. 13 shows a cross-sectional view of a portion of the carriagetranslating mechanism of FIG. 12.

In FIGS. 1, 2 and 3, a video disc player 20 (incorporating the carriagetranslating mechanism of the aforesaid Stave application) includes ahousing 22 which is provided with an input slot 24 at the front endthereof, through which a record caddy is inserted for loading anenclosed record into the player. A turntable 26 includes a recordcentering spindle 28, and a soft annular pad 30 for supporting therecord. The turntable diameter is made less than the record diameter,and the soft annular pad supports the record in the grooved area.

The turntable 26 is driven by a motor 32 (FIG. 1) to rotate at apredetermined speed within preset limits (e.g., 450 rpm±0.01%). U.S.Pat. No. 3,912,283 (Hammond, et al.), discloses an alternate form of aturntable drive system.

A platform 34, mounted on a shaft 36 which is located at the non-inputend of the housing 22, is subject to motion between an elevated position(FIG. 2) and a depressed position (FIG. 3). A pair of rails 38 and 40are disposed on the platform 34. The rails have grooves 42 and 44 forguiding insertion of a caddy into the housing along a path. The frontends of the caddy guiding grooves are aligned with the input slot 24when the platform is occupying the elevated position for permittinginsertion of a caddy into the player.

As shown in FIGS. 4 and 5, the record caddy 50 comprises an outer jacket52 and a record retaining member 54 removably located within the jacket.The retaining member comprises (1) an annular portion 56, that encirclesthe enclosed record 58, and (2) a spine portion 60, which serves as aclosure to keep dust and debris from entering the record enclosingcavity. The spine has an opening 62 into which the latch arms 70 and 72of a record extracting mechanism 74 (FIG. 1) protrude during arrival ofa record caddy at a fully inserted position in the player to effectrecord removal during subsequent caddy withdrawal.

The record extracting mechanism 74 is mounted on the platform 34. In themanner shown in FIG. 6, the extracting mechanism 74 includes latch arms70 and 72 pivotally secured to a platform-mounted bracket 76. The latcharms are alternated between an open condition (FIGS. 6 and 7) and aclosed condition (FIG. 8), in response to each caddy arrival at thefully inserted position in the player. The arrangement for rendering theextracting mechanism caddy responsive includes a pivotally-mountedactuating arm 78 disposed in the caddy path. The actuating arm advancesa ratchet 80, carrying a square-shaped cam 82, through 45 degrees eachtime a cover arrives at a fully inserted position in the player. Eachadvancement of the square-shaped cam changes the condition of latch armsfrom the condition they occupied prior to cover insertion to the othercondition thereof. Springs (not shown) are provided for returning theactuating arm to the rest position thereof, and to bias the latch armsinto engagement with the square-shaped cam 82. A pawl (not shown) isprovided to prevent the ratchet from rotating in the reverse directionwhen the actuating arm is returned to its rest position. U.S. Pat. No.4,109,919 (Elliott, et al.), discloses a suitable caddy-actuated recordextracting mechanism.

To load a record into the player, the latch arms 70 and 72 are disposedin the closed condition (FIG. 8), the platform 34 is disposed in theelevated position (FIG. 2) and an occupied caddy is inserted through theinput slot 24 along the caddy guiding grooves 42 and 44. The latch armsenter the opening 62 in the spine 60 as the caddy reaches the fullyinserted position in the player. The engagement of the caddy with theactuating arm 78 indexes the latch arms into the spread apart condition(FIG. 7), whereby the retaining member and the associated record arelocked to the platform. Subsequent withdrawal of the caddy removes therecord therefrom, thereby retaining the record in the player resting onthe raised platform (FIG. 9). To transfer the retained record to theturntable, the platform is lowered to the depressed position (FIG. 10).

For record retrieval, the above sequence is reversed. The platform, withthe record resting thereon, is raised (FIG. 9). The inner diameter of anopening 90 in the platform 34 is sufficiently less than the recorddiameter to positively insure lifting of the retained record duringupward motion of the platform. The platform is provided with a set ofdepressible lifting pads 92, 93, 94, 95 and 96 (FIG. 1) to align therecord resting thereon with the caddy guiding grooves 42 and 44 to causereturn of the record into an empty caddy during insertion thereof intothe player. As a caddy is loaded into the player, the leading edgethereof depresses the lifting pads to allow forward motion of the caddy.The engagement of the caddy with the actuating arm 78 reindexes thelatch arms to the closed condition (FIG. 8), thereby freeing the recordfrom the player. Subsequent caddy withdrawal removes the enclosed recordtherewith.

The rails 38 and 40 are further provided with a second set of grooves100 and 102 (FIGS. 2 and 3) for guiding a carriage 104 along a secondpath parallel to the caddy path (front-and-back). The carriage isprovided with a pair of projections (not shown), which are respectivelyreceived in the carriage guiding grooves.

A pickup cartridge 106, carrying a groove-riding stylus 107 at the endof a stylus arm 108, is installed in a compartment provided in thecarriage 104 (FIG. 1). The carriage is translated during playback alongthe rails toward the turntable center (a direction opposite to thedirection of caddy insertion) in correlation with the speed of rotationof the turntable in the manner hereinafter described. An arm-stretcherapparatus 109 oscillates the pickup stylus back-and-forth along thegroove so as to offset cyclical errors in stylus/record relativevelocity. U.S. Pat. No. 4,030,124 (Allen), discloses a pickup cartridgesuitable for use with the player described herein. A suitablearmstretcher apparatus is shown in U.S. Pat. No. 3,983,318 (Miller, etal.).

A pair of racks 110 and 112 are respectively secured to the platformrails 38 and 40. A shaft 114, carrying a set of pinions 116 and 118, isrotatably secured to the carriage 104 (FIG. 1). A respective one of thepinions engage a respective one of the racks to ensure that the carriagepath lies radially of a turntable-supported record throughout theoperating range thereof.

Prior to playback, the carriage is restored to a starting position. Theresetting of the carriage to the starting position is done automaticallywhen a caddy is inserted, for example, to retrieve a record, resting onthe platform while it is disposed in the raised position, from theplayer. The location of the caddy path relative to the carriage path issuch that a caddy engages the carriage during insertion thereof into theplayer. The player is dimensioned such that the arrival of thecarriage-engaging caddy at the fully inserted position in the playercoincides with the arrival of the engaged carriage at the startingposition.

For playback, the platform, with a retained record resting thereon, isdepressed to transfer the record to the turntable. The carriage istranslated during playback along the rails in a direction opposite tothe direction of caddy insertion in correlation with the speed ofrotation of the turntable. In addition to normal correlated translationof the carriage during playback, the carriage is translatable in eitherdirection at a speed independent of the speed of rotation of theturntable during active search.

The carriage drive mechanism includes an endless play belt 130, anendless search belt 132 and a carriage-mounted, mechanical toggle switch134 (FIG. 1). The toggle switch selectively connects one of the twobelts to the carriage to effect carriage translation by a selected oneof the belts. The play belt is driven in correlation with the turntablerotational speed, and in a direction causing carriage translation towardthe record center. The search belt is driven independent of theturntable rotational speed, and in either direction. The belts aredriven in the manner described hereinafter. The play belt is disposedabout a pair of pulleys 136 an 138, and the search belt is disposedabout an additional set of pulleys 140 and 142. Pulleys 136 and 140 areloosely mounted on the platform shaft 36 for motion independent thereof.The other pulleys 138 and 142, serving as idling members, are freelymounted for rotation about a pin 144 secured to the platform 34, andextending parallel to the platform shaft 36. The respective locations ofthe pulleys are such that the belts lie along a path parallel to thecarriage path.

The mechanisms for driving the two belts will now be described. As shownin FIG. 1, a turntable-driven pulley 150 and a thumbwheel-driven pulley152 are also loosely mounted on the platform shaft 36 for motionindependent thereof. The plat belt driving pulley 136 and the searchbelt driving pulley 140 are respectively secured to the turntable-drivenpulley 150 and the thumbwheel-driven pulley 152 for rotation therewith.

The turntable-driven pulley 150 is coupled to a pulley 154 which, inturn, is driven by the turntable drive motor 32 via a drive chain 156.The selection of proper gear ratios permits carriage translation incorrelation with the radial motion of the groove-riding stylus duringplayback.

A serrated thumbwheel 160 is rotatably mounted in the housing 22, andhas a portion, which is accessible to the user of the player through aslot in the front instrument panel 230 of the player. A pulley 162 ismounted coaxially with the thumbwheel for rotation therewith. Thecoaxially mounted pulley drives the thumbwheel-driven pulley 152 bymeans of endless belts 164 and 166 via an intermediate pulley 168. Itwill be seen that the speed of the bidirectional search belt iscontinuously variable over a range of speeds in either direction byutilizing the manually-actuated thumbwheel. All of the endless belts andthe pulleys herein used are equipped with teeth to provide nonslipcoupling.

An apparatus 170 (FIGS. 1 and 11) for causing motion of the pickupstylus between a lowered position, permitting engagement between thestylus and a turntable-supported record, and a raised position,precluding stylus/record engagement, is mounted in the carriage 104. Thepickup stylus is lowered for engagement with a turntable-supportedrecord during playback and active search. The pickup stylus is raisedwhen the player is in a pause mode and when the carriage reaches anend-of-play position.

Essentially, as shown in FIG. 11, the stylus lifting/lowering apparatus170 includes a stylus arm rest 172 mounted for motion between anelevated position and a depressed position. The stylus arm rest in theelevated position supports the stylus arm 108 (FIG. 1) in a mannerprecluding stylus/record contact. The stylus arm rest in the depressedposition permits the stylus arm to occupy a lowered position. Thelowered position of the stylus arm is such that the stylus/recordcontact is established when the carriage is in the over-record playposition. An electromagnet 174 is energized to repel a permanent magnet176 secured to the stylus arm rest to dispose the stylus arm rest in thedepressed position. A leaf spring 178 secured to the stylus arm restlifts the stylus 107 off the record when the electromagnet isde-energized. A selectively actuated plunger 179 depresses the stylusarm rest when actuated. U.S. Pat. No. 4,053,161 (Bleazey, et al.),discloses such stylus lifting/lowering apparatus.

Disposed in the carriage are pickup circuits coupled to the output ofthe groove-riding stylus for developing a signal representative of theinformation stored on the turntable-supported record. Signal processingcircuits, coupled to the output of the pickup circuits, are located inthe housing for developing a signal suitable for application to atelevision receiver for audio/visual presentation of the informationstored on the record. U.S. Pat. No. 4,080,625 (Kawamoto, et al.),discloses suitable pickup circuits. U.S. Pat. No. 4,097,899 (Yu),illustratively describes signal processing circuits.

To obtain various special effects, the mechanical toggle switch 134 isthrown into an active search mode to connect the carriage to thevariable speed, bidirectional search belt 132 to the exclusion of theconstant speed, unidirectional play belt 130. It will be noted that inthe active search mode, as well as in the play mode, the styluslifting/lowering apparatus permits stylus/record engagement. To realize,for example, fast forward motion, the carriage is translated at a rapidrate in the forward direction by rotating the thumbwheel 160 atappropriate speed in the required direction, while the stylus is allowedto ride on the record. The reverse motion can be obtained by translatingthe carriage in the reverse direction (i.e., away from the turntablecenter or toward the starting position). To obtain repeat play effect,the carriage is allowed to remain stationary, thereby causing thegroove-riding stylus to repetitively trace a selected set of grooveconvolutions.

The platform lifting/lowering mechanism will now be described inconjunction with FIGS. 1-3. A function selection lever 250 secured to arotatably mounted wheel 252, extends through a slot provided in thefront instrument panel of the player. The function selection lever ismoved to the positions shown in FIGS. 2 and 3, respectively, to raiseand lower the platform. In the raised position of the platform, thefront ends of the caddy guiding grooves 42 and 44 are aligned with theinput slot to permit caddy insertion and extraction. The depression ofthe platform, with a retained record resting thereon, effects transferto the retained record to the turntable for playback. The functionselection lever may also serve to shut off power to the player, forexample, when it is shifted to a position beyond the caddy in/outposition (FIG. 2).

The function selection wheel is provided with peripheral, axial notches254 and 256 corresponding to the raised and lowered position of theplatform. A detent 258, secured to a pivotally mounted lever 260, isreceived in one of the notches to releasably hold the function selectionwheel in a selected one of the positions thereof. A spring 262 urgesengagement between the detent and the periphery of the functionselection wheel 252.

The linkage between the function selection lever and the platformincludes a pair of spaced levers 264 and 266 secured to a rotatablymounted shaft 268. A set of platform-engaging rollers 270 and 272 arerespectively disposed at the free ends of the spaced levers. As shown inFIG. 1, an endless toothed belt 274 is disposed about a toothed pulley276, securely mounted on the shaft 268, and another toothed pulley 278,mounted coaxially with the function selection wheel for rotationtherewith. The relative angular location of the spaced levers 264 and266 is such that the motion of the function selection lever between thetwo positions causes corresponding motion of the platform between theelevated and the depressed position.

A rotatably-mounted dial 290 (FIG. 1), bearing an indicia indicative ofthe respective playing times associated with distance traveled by thecarriage from a starting position, is visible through a readout windowprovided in the front instrument panel of the player. A cord 292 extendsbetween the carriage 104 and the indicia bearing dial such that thedisplacement of the carriage along the guiding rails effectssynchronized rotation of the dial. A torsion spring 294 is disposedabout the axis of rotation of the dial such that it gets coiled duringtranslation of the carriage away from the starting position, wherebyenergy is stored in the torsion spring. The coiled spring applies aforce to the carriage in a sense urging carriage travel toward thestarting position. The applied force aids resetting of the carriage tothe starting position, when it is at a position other than the startingposition, during a caddy insertion. The cord 292 is passed over agrooved pulley 296 and another grooved pulley 298. The pulley 298 iscoaxially mounted on the platform shaft. One end of the cord is fastenedto the carriage-mounted block 180, and a portion at the other endthereof is wrapped around the stem portion of the dial. The stiffness ofthe torsion spring is selected to give the desired feel to the user ofthe player as he inserts a caddy into the player to restore the carriageto the starting position.

The input slot is covered with a flap for keeping dust and debris fromentering the record chamber in the player. When the player is disposedin the caddy in/out mode (FIG. 2) by means of the function selectionlever, the flap uncovers the input slot to allow caddy insertion andextraction. In other modes of the player, the flap remains closed.

It will be noted that both the caddy guiding grooves and the carriageguiding grooves are integrally molded with the platform to provide asingle-main-frame construction. This permits a precise positioning ofthe caddy relative to the carriage and the carriage relative to theturntable throughout the operating range.

The mounting of the play belt driving pulley 136, the search beltdriving pulley 140, the turntable-driven pulley 150, thethumbwheel-driven pulley 152 and the grooved pulley 298 on the platformshaft 36 permits platform motion without disturbing the rest of theplayer system.

Shown in FIGS. 12 and 13 is a novel carriage translating mechanism 400,built in accordance with the instant invention, for providing activescanning and special effect features. The novel carriage translatingmechanism is suitable for substitution in place of the carriagetranslating mechanism of the aforesaid Stave application in the playerof FIGS. 1-3. The advantages of the novel carriage translating mechanismare that it eliminates the need for separate play and search belts, andthe need for clamping and unclamping of these belts.

As shown in FIGS. 12 and 13, the platform 34 is pivotally mounted aboutthe shaft 36. It will be seen that the platform rail 40 is provided withthe caddy guiding groove 44 and the carriage guiding groove 102. Thepickup carriage 140 is slidably mounted on the platform for translationalong a path lying substantially parallel to the caddy path in themanner hereinbefore discussed. For reasons of clarity, the rack andpinion arrangement (shown in FIGS. 1-3) for assuring radial translationof the pickup carriage is not illustrated in FIG. 12.

The novel carriage translating mechanism includes a common drive belt402 disposed about a carriage driving pulley 404 and an idler pulley406. The carriage driving pulley 404 is loosely mounted on a shaft 408for rotation independent thereof. A pair of spaced members 410 and 412,secured to the housing of the player, support the shaft 408 coaxiallywith the platform shaft 36 for translation along a path parallel to thecommon axis. The idler pulley 406 is rotatably mounted about a pinsecured to the platform. The carriage is fixedly secured to the commondrive belt 402 by a clamp 414.

A first drive mechanism for translating the carriage during playbacktoward the turntable center at a speed correlated to the speed ofrotation of the turntable (while the stylus lifting/lowering apparatuspermits stylus/record engagement) includes an endless play belt 416disposed about a turntable driven pulley 418 and a second idler pulley420. The turntable driven pulley 418 is loosely mounted on the coaxialshaft 408 for motion independent thereof. The idler pulley 420 is drivenby the turntable motor, via another drive chain 422, to rotate at aspeed which causes the carriage to move in synchronism with thegroove-riding pickup stylus during playback. The turntable driven pulley418 drives the carriage driving pulley 404 via a slip clutch 424 (FIG.13). The slip clutch 424 comprises a friction plate 426 fixedly securedto the turntable driven pulley 418 and a coil spring 428 disposed aboutthe coaxial shaft 408 to urge engagement between the carriage drivingpulley 404 and the friction plate. The coil spring 428 is seated in arecess 430 provided in the carriage driving pulley 404, and isinterposed between a retainer 432 securely mounted on the coaxial shaft408 and a shoulder portion 434 of the recess. A second retainer 436 issecured at the other end of the coaxial shaft 408 to limit axialmovement thereof within a given range.

A second drive mechanism for translating the carriage (during, forexample, active searching) toward and away from the turntable center ata speed independent of the turntable rotational speed (while the styluslifting/lowering apparatus allows stylus/record engagement) includes anendless search belt 438 disposed about another portion of carriagedriving pulley 404 and a pulley (not shown) mounted coaxially with arotatably mounted, serrated thumbwheel 440 for rotation therewith. Allthe endless belts and pulleys herein used are equipped with teeth toprovide a nonslip coupling between the respective members.

For active scanning, the carriage 104 can be translated at a speedvariable over a range of speeds, and in either direction, byappropriately turning the thumbwheel 440 (while stylus/record engagementis permitted by the stylus lifting/lowering apparatus). The slip clutch424 allows wresting of control of the common drive belt 402 by thethumbwheel 440, from the first drive mechanism, when the thumbwheel ismanually turned. Additionally, the slip clutch permits restoration ofthe carriage 104 to the starting position, when the carriage is at aposition other than the starting position, during a caddy insertion.

It is desirable that translation of the carriage toward the turntablecenter by virtue of the first drive mechanism resumes upon cessation ofoperation of the thumbwheel without delay due to effects of backlash inthe first drive mechanism. Any delay in resumption of the normaltracking movement of the carriage upon cessation of active searching isannoying to the listener/viewer. To provide a substantially instantresumption of playback, a drag mechanism 450 is provided. The dragmechanism 450 comprises a second friction plate 452 fixedly secured tothe support member 412 and a second coil spring 454 disposed about thecoaxial shaft 408 to urge contact between the thumbwheel driven pulley418 and the friction plate. The coil spring 454 is seated in a cavity456 provided in the turntable driven pulley 418, and is interposedbetween a flange portion of an adjustable retaining sleeve 458 and abase portion 460 of the cavity. The position of the retaining sleeve 458with respect to the support member 412, and hence the force with whichthe turntable driven pulley 418 is applied against the friction plate452, is variably adjusted by means of a nut 462 cooperating with theperipheral threads disposed on the stem portion of the retaining sleeve.The applied force is adjusted to a level such that the drag torque (dueto friction between the turntable driven pulley 418 and the frictionplate 452) exceeds the torque developed between the carriage drivingpulley 404 and the turntable driven pulley via the slip clutch 424,thereby preventing reverse rotation of the turntable driven pulley dueto effects of backlash, when the carriage driving pulley is rotated inthe reverse direction by the thumbwheel 440 to cause the carriage tomove away from the turntable center. The normal translation of thecarriage is hence instantaneously resumed without delay when thethumbwheel 440 is released.

In such players, where the caddy pushes the carriage back to thestarting position, it is desirable, as previously indicated, to reducethe force required to reset the carriage, and to provide a neutral, freeflowing feel to the user of the player during such caddy insertion. Thedial mechanism hereinbefore disclosed serves to, in addition toindicating the radial position of the carriage, aid restoration ofcarriage to starting position during a caddy insertion. When the novelcarriage translating mechanism 440 is employed in place of the carriagetranslating mechanism of the aforesaid Stave application in the playerof FIGS. 1-3, the thumbwheel 440 which is fixedly coupled to thecarriage 104 can be marked with appropriate indicia, and be used toindicate the radial position of the carriage instead of theabove-mentioned dial mechanism. In such a case, the dial mechanism maybe eliminated altogether. A mechanism, suitable for use in such aplayer, for aiding carriage restoration during a caddy insertion willnow be described.

As shown in FIG. 13, the aiding mechanism 470 comprises a first cammember 472 secured to the platform shaft 36 and a second, juxtaposed cammember 474 fixedly mounted on the coaxial shaft 408. The constructionand location of the cam members are such that when the platform 34 israised to the elevated position (FIG. 2), for example, to retrieve arecord from the player, the platform-mounted cam member 472 allows thecam member 474 to shift to the left, as viewed at FIG. 13, whereby theclutch spring 428 is caused to relax reducing the slip clutch engagementforce. The reduction in slip clutch engagement force permits slippagebetween the carriage driving pulley 404 and the turntable driven pulley418 during restoration of the carriage by the caddy to the startingposition when the platform is depressed, for example, to transfer aretained record to the turntable for playback, the slip clutchautomatically reengages to provide the required carriage driving torqueduring playback.

Filed concurrently herewith are the following U.S. patent applications,Ser. No. 964,531,: (1) application of L. A. Torrington, entitled, "VIDEODISC PLAYER," (2) application Serial No. 964,537 of L. A. Torrington andJ. A. Allen, entitled, "VIDEO DISC PLAYER HAVING UNITARY RECORD HANDLINGPLATFORM CONSTRUCTION," (3) application, Serial No. 964,536, of J. A.Allen, entitled "CARRIAGE TRANSLATING APPARATUS FOR VIDEO DISC PLAYER,"(4) application, Serial No. 964,534 of F. R. Stave, entitled "VIDEO DISCPLAYER HAVING MANUAL SCANNING FACILITY," (5) application, Serial No.964,535 of F. R. Stave, entitled "APPARATUS FOR FACILITATING CARRIAGERETURN IN VIDEO DISC PLAYER," (6) application, Serial No. 964,532 of F.R. Stave, entitled "VIDEO DISC PLAYER HAVING RECORD SIDE IDENTIFICATIONAPPARATUS," (7) application, Serial No. 964,533, of C. F. Coleman,entitled "VIDEO DISC PLAYER HAVING MODULAR CONSTRUCTION," (8)application, Ser. No. 964,529, of L. D. Huff, entitled "TOGGLE MECHANISMFOR VIDEO DISC PLAYER," (9) application, Serial No. 964,528 of L. A.Torrington, entitled, "RECORD SIDE IDENTIFICATION APPARATUS FOR VIDEODISC PLAYER," (10) application, Ser. No. 964,527 of L. A. Torrington andL. D. Huff, entitled "CONSTANT DRAG CARRIAGE TRANSLATING MECHANISM FORVIDEO DISC PLAYER," (11) application, Ser. No. 964,526, of L. A.Torrington and L. D. Huff, entitled "MECHANISM FOR AIDING CARRIAGERETURN IN VIDEO DISC PLAYER," (12) application, Ser. No. 964,633 of L.A. Torrington, entitled "VIDEO DISC PLAYER HAVING ADJUSTABLE END-OF-PLAYSWITCH," and (13) application, Ser. No. 964,643 of C. F. Coleman and N.L. Farley, entitled "CADDY-ACTUATED DECLUTCHING MECHANISM FOR VIDEO DISCPLAYER." Reference may be made to these applications for explanation ofvideo disc player features that may advantageously be employed with thepresent invention.

What is claimed is:
 1. A player for use with a disc record; said playercomprising:(A) a turntable for centering and supporting a record; (B)means for rotating said turntable; (C) a pickup stylus for recoveringprerecorded signals from a turntable-supported record during playback;(D) A carriage for supporting said pickup stylus; (E) means for causingmotion of said pickup stylus relative to said carriage between adepressed position, permitting stylus/record engagement, and an elevatedposition, precluding stylus/record engagement; (F) common carriagetranslating means including a first endless drive belt disposed about afirst pair of pulleys; (G) means for securing said carriage to saidfirst endless drive belt; (H) first means for utilizing said commoncarriage translating means for translating said carriage toward thecenter of said turntable at a speed correlated to the speed of rotationof said turntable while said stylus motion causing means permits saidstylus/record engagement; wherein said first utilizing means includes asecond endless drive belt disposed about a second pair of pulleys; oneof said second pair of pulleys being disposed coaxially with one of saidfirst pair of pulleys; and (I) second means for utilizing said commoncarriage translating means for translating said carriage toward and awayfrom said turntable center at a speed independent of the speed ofrotation of said turntable while said stylus motion causing means allowssaid stylus/record engagement; wherein said first utilizing meansincludes a slip clutch means interposed between said common carriagetranslating means and said one of said second pair of pulleys, wherebywresting of control of said common carriage translating means from saidfirst utilizing means by said second utilizing means is permitted bysaid slip clutch means upon activation of said second utilizing means.2. A player in accordance with claim 1 further including means forguiding said carriage along a path such that said pickup stylus istraversed along a direction radially disposed relative to saidturntable.
 3. A player in accordance with claim 1 wherein said secondutilizing means includes manually actuated means coupled to said one ofsaid first pair of pulleys for variably controlling the speed and thedirection of rotation of said one of said first pair of pulleys.
 4. Aplayer in accordance with claim 3 wherein said manually actuated meansincludes a rotatably mounted thumbwheel.
 5. A player in accordance withclaim 4 wherein said second utilizing means further includes a furtherpulley coaxially mounted with said one of said first pair of pulleys forrotation therewith, and means for coupling said thumbwheel to saidcoaxially mounted further pulley.
 6. A player in accordance with claim 5wherein said thumbwheel coupling means comprises a still further pulleycoaxially mounted with said thumbwheel for rotation therewith, and athird endless drive belt disposed about said coaxially mounted furtherpulleys.